1. Field of the Invention
The present inventions relate to delustrants composed of polyimide powder, polyimide films incorporating the polyimide powder delustrant, and manufacture methods thereof.
2. Description of the Related Art
Polyimide films are widely used in electronic products. Owing to high surface flatness, the polyimide film may cause light reflection that may be uncomfortable to viewing and causes eyestrain during extensive use. This effect may be magnified in color films which can render the reflected light even more significant to the viewer.
In order to reduce the gloss of the polyimide film, some approach may incorporate a delustrant into the polyimide film to increase its surface roughness, so that incident light can be scattered. Conventional delustrants may include inorganic and organic compounds.
Examples of inorganic compounds used as delustrant can include silicon oxide, aluminum oxide, calcium carbonate, barium sulphate, titanium dioxide and the like. However, inorganic particles have a relatively high dielectric constant, which may confer poor insulation property to the film.
Examples of organic compounds used as delustrant can include polycarbonate (PC), polystyrene (PS), polymethylmethacrylate (PMMA), polyethylene, polypropylene, polyethylene terephthalate (PET), epoxy resin and the like. However, the organic compound cannot tolerate a temperature above 250° C., which is approximately the temperature at which chemical conversion occurs in the manufacture of the polyimide film. As a result, using organic compounds in the manufacture of the polyimide film may produce defects such as cracks or apertures, or form spots of non-uniform color due to uneven melting.
Therefore, there is a need for a polyimide film with desirable properties and low gloss, and address at least the aforementioned issues.